[ns] ns 2.28 default values for IEEE 802.11

[Sven Kopetzki]

I want to set phy and mac parameters for 802.11a and 802.11b.
I wonder about some duplicate default values in tcl-files of ns2.28.
During a search within tcl-files I found some duplicate entries
(disregarding upper and lower case) e.g. for CWMin_, CWMax_, SlotTime_
and SIFS_ in
~\ns-allinone-2.28_edca\ns-2.28\tcl\lib\ns-default.tcl and
~\ns-allinone-2.28_edca\ns-2.28\tcl\lan\ns-mac.tcl

As far as I know ns-mac.tcl is only used to set basicRate_ and
dataRate_, right?

Where do I have to set phy and mac specific parameters (e.g. slottime)?
ns-default.tcl seems to be more up to date.

Which of the parameters could be set without re-compilation?

Thanks in advance
Sven